scholarly journals Bioturbation by endogeic earthworms facilitates entomopathogenic nematode movement toward herbivore-damaged maize roots

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Sandrine Fattore ◽  
Zhenggao Xiao ◽  
Adrienne L. Godschalx ◽  
Gregory Röder ◽  
Ted C. J. Turlings ◽  
...  

AbstractEntomopathogenic nematodes (EPNs) have been extensively studied as potential biological control agents against root-feeding crop pests. Maize roots under rootworm attack have been shown to release volatile organic compounds, such as (E)-β-caryophyllene (Eβc) that guide EPNs toward the damaging larvae. As yet, it is unknown how belowground ecosystems engineers, such as earthworms, affect the biological control capacity of EPNs by altering the root Eβc-mediated tritrophic interactions. We here asked whether and how, the presence of endogeic earthworms affects the ability of EPNs to find root-feeding larvae of the beetle Diabrotica balteata. First, we performed a field mesocosm experiment with two diverse cropping systems, and revealed that the presence of earthworms increased the EPN infection potential of larvae near maize roots. Subsequently, using climate-controlled, olfactometer-based bioassays, we confirmed that EPNs response to Eβc alone (released from dispensers) was two-fold higher in earthworm-worked soil than in earthworm-free soil. Together our results indicate that endogeic earthworms, through burrowing and casting activities, not only change soil properties in a way that improves soil fertility but may also enhance the biocontrol potential of EPNs against root feeding pests. For an ecologically-sound pest reduction in crop fields, we advocate agricultural practices that favour earthworm community structure and diversity.

Agriculture ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 60
Author(s):  
Onja Ratsiatosika ◽  
Malalatiana Razafindrakoto ◽  
Tantely Razafimbelo ◽  
Michel Rabenarivo ◽  
Thierry Becquer ◽  
...  

The effects of earthworm inoculation and cropping systems on upland rice systems were examined over a four-year period in the Highlands of Madagascar. Each year, endogeic earthworms Pontoscolex corethrurus (Rhinodrilidae) were inoculated (EW+) at a density of 75 ind m−2 or were not inoculated (EW0). Inoculation was tested in three cropping systems: conservation agriculture (CA) and traditional tillage with or without residues restitution. Soil and plant properties were measured during the first three years while soil biological properties were assessed at the fourth year. At the end of the experiment, earthworm density was three-fold higher in EW+ than in EW0, demonstrating the success of the inoculation. Earthworm density was more important in CA than in tillage systems. Earthworm inoculation had higher significant effects on soil and plant properties than cropping systems. Earthworm inoculation had positive effects on soil macroaggregation (+43%), aboveground biomass (+27%), rice grain yield (+45%), and N grain amount (+43%). Intensifying earthworm activity in field conditions to meet the challenge of ecological transition is supported by our study.


2010 ◽  
Vol 54 (3) ◽  
pp. 166-171 ◽  
Author(s):  
Z. Ipek Ekmen ◽  
Selcuk Hazir ◽  
Ibrahim Cakmak ◽  
Nurdan Ozer ◽  
Mehmet Karagoz ◽  
...  

2004 ◽  
Vol 31 (2) ◽  
pp. 86-91 ◽  
Author(s):  
D. T. Gooden ◽  
H. D. Skipper ◽  
J. H. Kim ◽  
K. Xiong

Abstract Rhizobacteria play an important role in sustainable agriculture via plant growth and biological control of pests in a number of ecosystems. Understanding the interactions of crop rotation and rhizobacteria on peanut production is a critical research need. Development of a database on the rhizobacteria obtained from continuous and rotational fields of peanut was initiated in 1997 and terminated in 2000. Peanut was planted in monoculture for 4 yr. In rotational plots, peanut, cotton, corn, and peanut were planted in sequence. Rhizobacteria were isolated from the roots of crop plants grown in a Norfolk soil near Florence, SC. These isolates were identified by composition of fatty acids from gas chromatography analysis (GC/FAME). Arthrobacter and Bacillus were the major genera from non-rhizosphere soils. At initiation of this study in July 1997, the plots selected for continuous peanut had more diversity in rhizobacteria than those plots selected for rotation. In July 2000, rhizobacteria diversity was greater from peanut roots in the rotation cropping system than continuous peanut. Even though rhizobacteria diversity was greater in the rotation system, higher peanut yields were recorded in the continuous peanut system in 2000. Burkholderia spp. were always isolated from the peanut and other crop rhizospheres at each sampling date.


2011 ◽  
Vol 35 (6) ◽  
pp. 1149-1156 ◽  
Author(s):  
Viviane Santos ◽  
Alcides Moino Junior ◽  
Vanessa Andaló ◽  
Camila Costa Moreira ◽  
Ricardo Alves de Olinda

Entomopathogenic nematodes (EPNs) are used in biological control of soil insects and show promise in the control of D. speciosa. The objective of this work was to evaluate the potential of native and exotic entomopathogenic nematode isolates in the control of D. speciosa under laboratory and greenhouse conditions. Results showed that all of EPNs caused larval mortality. The most virulent were Heterorhabditis sp. RSC01 (94%), Steinernema glaseri (84%), Heterorhabditis sp. JPM04 (82%) and Heterorhabditis amazonensis RSC05 (78%). There was no effect of the Heterorhabditis sp. RSC01 and S. glaseri isolates on eggs. The maximum mortality of D. speciosa larvae by Heterorhabditis sp. RSC01 was observed at a concentration of 300 IJ/ insect, while by S. glaseri observed the highest mortality at the concentration of 200 IJ/ insect. The Heterorhabditis sp. RSC01 isolate caused over 80% pupal mortality at a concentration of 250 IJ/insect. The virulence of Heterorhabditis sp. RSC01 and S. glaseri was affected by temperature. The Heterorhabditis sp. RSC01 isolate caused reduction in larva survival under greenhouse conditions at all of the tested concentrations and there was no difference in mortality among different concentrations of infectid juveniles.


Agronomy ◽  
2019 ◽  
Vol 9 (3) ◽  
pp. 127 ◽  
Author(s):  
Arjun Kafle ◽  
Kevin Cope ◽  
Rachel Raths ◽  
Jaya Krishna Yakha ◽  
Senthil Subramanian ◽  
...  

Phosphorus is an essential macronutrient required for plant growth and development. It is central to many biological processes, including nucleic acid synthesis, respiration, and enzymatic activity. However, the strong adsorption of phosphorus by minerals in the soil decreases its availability to plants, thus reducing the productivity of agricultural and forestry ecosystems. This has resulted in a complete dependence on non-renewable chemical fertilizers that are environmentally damaging. Alternative strategies must be identified and implemented to help crops acquire phosphorus more sustainably. In this review, we highlight recent advances in our understanding and utilization of soil microbes to both solubilize inorganic phosphate from insoluble forms and allocate it directly to crop plants. Specifically, we focus on arbuscular mycorrhizal fungi, ectomycorrhizal fungi, and phosphate-solubilizing bacteria. Each of these play a major role in natural and agroecosystems, and their use as bioinoculants is an increasing trend in agricultural practices.


2021 ◽  
Vol 3 ◽  
Author(s):  
Giovanni Antonio Puliga ◽  
Jan Thiele ◽  
Hauke Ahnemann ◽  
Jens Dauber

In agroecosystems, crop diversification plays a fundamental role in maintaining and regenerating biodiversity and ecosystem services, such as natural pest control. Temporal diversification of cropping systems can affect the presence and activity of natural enemies by providing alternative hosts and prey, food, and refuges for overwintering. However, we still lack studies on the effects of temporal diversification on generalist predators and their biocontrol potential conducted at field scale in commercial agricultural settings. Here, we measured proxies of ecosystem functions related with biological pest control in 29 commercial agricultural fields characterized by cereal-based cropping system in Lower-Saxony, northern Germany. The fields differed in the number of crops and cover crops cultivated during the previous 12 years. Using the Rapid Ecosystem Function Assessment approach, we measured invertebrate predation, seed predation and activity density of generalist predators. We aimed at testing whether the differences in the crop rotations from the previous years would affect activity of predators and their predation rates in the current growing season. We found that the length of the crop rotation had neutral effects on the proxies measured. Furthermore, predation rates were generally lower if the rotation comprised a higher number of cover crops compared to rotation with less cover crops. The activity density of respective taxa of predatory arthropods responded differently to the number of cover crops in the crop rotation. Our results suggest that temporal crop diversity may not benefit the activity and efficiency of generalist predators when diversification strategies involve crops of very similar functional traits. Adding different resources and traits to the agroecosystems through a wider range of cultivated crops and the integration of semi-natural habitats are aspects that need to be considered when developing more diverse cropping systems aiming to provide a more efficient natural pest control.


2010 ◽  
Vol 25 (2) ◽  
pp. 105-132
Author(s):  
Radmila Petanovic ◽  
Dejan Marcic ◽  
Biljana Vidovic

Part one discusses some principal mite pests in agroecosystems and urban horticulture in European countries, Serbia and its neighbouring countries focusing primarily on issues with regard to plant production, novel methods and approaches in applied acaralogy. Part two displays some major properties of acaricides inhibiting respiration, growth and development and other synthetic substances with acaricide action on the market in the last decade of the 20th century and the first decade of the 21st century. Also some products of natural origin (azadirachtin, oils, micoacaricides) are said to be gaining in importance. Issues with regard to the fact that mites can readily develop resistance to acardicides are discussed and a survey on the results of biochemical, physiological and genetical causes of resistance are analyzed. Some basic principles of biological control of phytophagous mites and modern advances and approaches are discussed as well as current knowledge on host plant resistance to mites. Eventually, the possibility of using a combination of selective acaricides and biological control agents is discussed but also the inclusion of other modes of control (agricultural practices and physical measures) expected to contribute to an integrated management of pest populations.


Agronomy ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 29 ◽  
Author(s):  
Liliane Ngoune Tandzi ◽  
Charles Shelton Mutengwa

Standardization of crop yield estimation methods at various levels of farming helps to obtain accurate agricultural statistics as well as assessing the suitability of agricultural practices under various production conditions. The current paper reviews various maize yield estimation methods, taking into account available yield parameters, and it also analyses the yield gap between maize potential and attainable yield. The easiest and more reliable methods of yield estimation are based on yield parameters collected from the field. However, farmer estimation methods are cheaper and faster compared to any other method of yield estimation from farmers’ fields. This paper also elaborates on the importance of the use of more complex methods for yield estimation, such as remote sensing and crop modelling. These complex methods are more accurate and can predict yield before field harvest with less deviation from the exact harvest yield. However, they are very expensive and not efficient for small plots of land (less than 1 ha). Factors that contribute to the gap between potential and actual yield include poor implementation of agricultural policies, strict regulation of fertilizer inputs, vulnerability of smallholder cropping systems to adverse climatic conditions, occurrence of biotic and abiotic constraints, as well as unavailability of seeds and labor.


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